Infrared to vacuum ultraviolet optical properties of 3C, 4H and 6H silicon carbide measured by spectroscopic ellipsometry

Abstract

Spectroscopic ellipsometry in the infrared to vacuum ultraviolet (IR–UV SE) is used to determine the optical properties of the three most common polytypes of silicon carbide (SiC), namely the 3C, 4H and 6H polytype in the photon energy region between 0.03 and 9 eV. The results in the IR region, obtained by utilizing a factorized harmonic form of the dielectric function, contain information on free carrier concentrations, phonon modes and effective masses. Since the 4H and 6H polytype crystallizes in a hexagonal frame, it is necessary to consider anisotropy. We report both ordinary ( ε⊥ c-axis) and extra-ordinary ( ε‖ c-axis) dielectric function data of 4H- and 6H-SiC. The data in the UV region are also compared to ab initio calculations. Critical point energies were found using both real and reciprocal space analysis.